Castlepook’s reindeer femur raises a compelling distinction between evidence for a possible human visit and evidence for enduring occupation. Its suggested cut mark gains environmental context from Derryvree’s productive treeless wetlands and Castlepook’s varied cold-adapted fauna, yet cave deposits combine remains from different periods and processes. The article therefore presents Ice Age Ireland as ecologically connected and potentially accessible, while leaving the scale of human activity unresolved. Comparing this Irish evidence with documented Upper Palaeolithic sites in north-west Europe, what criteria should guide interpretations of brief visits, seasonal use, or settlement, and which discoveries would strengthen one explanation over another?